i-adjective
stinking of urine; smelling like pee
Literal, often derogatory description of a strong urine odor, typically from a person, clothing, or a place.
トイレの前が小便臭い。
It smells like urine in front of the toilet.
その老人はいつも小便臭い服を着ている。
That old man always wears clothes that stink of urine.
i-adjective
childish; immature; inexperienced
Derogatory figurative use, likening someone's behavior or attitude to the smell of a baby's urine; implies a lack of maturity or worldliness.
そんな考え方は小便臭いよ。
That way of thinking is so childish.
彼の意見はまだ小便臭い。
His opinions are still immature.